That seems to be quite a grandiose, and improbable claim, does it not?

The people closely associated with the namesake of female canines are suffering from a nondescript form of lunacy.
"Anti-environmentalism is like standing in front of a forest and going 'quick kill them they're coming right for us!'" - Jake Farr-Wharton, The Imaginary Friend Show.

Of all the human races that are inferior, trolls are the most inferior.

Regarding the original post as to what african americans contributed:

Lewis Latimer: Inventor of the filament of light bulbs (yeah, next time you turn on a light think about that)
George Carver: Peanut butter (if you don't like PBJ sandwiches fuck you)
Martin Luther King: Lead a pretty awesome movement, might want to check a history book and read about it.
William Bennett: Mass spectrometer. Next time you get a modern xray remember at some point a black dude was responsible for the progress to modern x-rays. So if you get a broken leg, think of him.
Patricia Bath: Laser surgery for cataracts. (helping the blind see better than jesus!)

Better to light a candle than curse the darkness my friend. If you forever judge people as "groups" then you are destined to have a small mind and a pitiful loss of experience in life. You call it PC -I'd call it perspective. Spend some time in Africa or read a book about how someone else did and learned such things first hand.